The present invention relates to improved methods for cleaning lenses. More specifically, this invention relates to improved methods for cleaning and disinfecting contact lenses through the use of enzymatic cleaners wherein the time interval needed to complete the process can be significantly reduced thereby providing greater flexibility and convenience to the wearer.
In the normal course of wearing contact lenses, tear films and debris consisting of proteinaceous, oily and sebaceous matter have a tendency to deposit and build-up on lens surfaces. As part of the routine care regimen, hydrophilic gel lenses or soft contact lenses, for example, must be cleaned to remove these tear film deposits and debris. Otherwise, if not removed, both wettability and optical clarity of the lenses can be reduced. Because the composition of such deposits is mainly proteinaceous, enzyme cleaning solutions containing mainly proteolytic enzymes have been widely used.
Although most enzyme cleaners are generally regarded as efficacious and safe, they nevertheless have certain shortcomings which create inconveniences for the user. Heretofore, the process of cleaning contact lenses with enzymatic cleaners involved two main steps: the first consisting of the cleaning phase whereby coated lenses are soaked in the enzyme solution at ambient temperature conditions, i.e. . . . cold soaking, for a period of at least 2 hours and up to 12 hours, and occasionally, overnight to achieve effective cleaning. At the conclusion of the cleaning step, the lenses must be disinfected. Disinfection normally requires exposing the lenses to a temperature of 80.degree. C. for at least 10 minutes. This is carried out by first immersing the lenses in a lens storage case with a second solution, such as preserved isotonic sterile saline followed by asepticizing in a heat disinfection unit. Such units have a heating cycle which normally takes about 1 hour to complete. Thus, the time needed to clean and disinfect soft contact lenses utilizing enzymatic cleaners can take up to 13 hours. Accordingly, there is a need for an abbreviated, more convenient means for cleaning contact lenses with enzyme cleaners which provides a greater degree of flexibility.
The present invention provides a less complex and more convenient regimen for enzymatic cleaning of contact lenses whereby actual cleaning and disinfection are carried out in the enzyme solution in a single step over a significantly reduced time period of 60 minutes or less. The method of present invention provides the added benefit of concurrent deactivation of the active enzymes by the time the cycle is completed. In addition to the greater convenience factor for the user, the improved methods for enzymatic cleaning are also more economic since only a single lens care solution is needed; whereas, previous methods required both a cleaning solution and another rinsing solution.